Personally I found that I'm more profitable in ring games. Ring games allow me to pick my tables. IE, I control where I sit and who I sit with. This is a big advantage.
Also, if I get sucked out on in a ring game I can rebuy, thereby retaining my image/position/reads/etc. But in a tournament or S&G one big suck out means you've lost all that and have to start a new game from scratch. Plus, at multi-table games you can get moved, which is harmful to the image you've guilt and your reads on the other players.
Oh yeah, and toward the end of a S&G, with rising blinds, there's a lot more luck involved and you *need* to make big/risky moves.
Of course, if you're a better tournament player than you are a ring game player, then by all means hit the S&G's.
Personally, I was a losing player in S&G's. But I recently started experimenting with the 2-payer HU S&G's and have won 5/6 of those. (The one loss coming from flopping a set of 4's, getting all-in, then losing when he made a set of Jacks on the river).
So I'm tempted to put more effort into those sort of S&G's.